Guard



E. BRUNS Feb. 21, 1939.

GUARD Fimled Feb. 18, 195s y i HT. m

fmefzfo?? m, m m m M Patented Feb. 21, 1939 UNITED STATES frfnfrr;NTOFFICE 2 Claims.

This invention relates to improvements in guards for machines which' areadapted, in operation, to discharge partic1es,such as particles ofgrinding wheels, particles of metal or glass, and which particles may bedriven into the eyes ofthe operator. VThe `guard is applicable, withbeneiicial results, to art glassA grinding and cutting machines, keymaking machines, jewelers Alathes andhgrinders and metal turning lathesand indeed to any machine which includes a high speed cutting" orabrasive wheel or other means which; in operation, is apt to throwoffparticles and which particles are likely to be quit-e hot.

The object of the inventionisto provide a transparentiguard adapted tobe held in a position between the point of 'removal of particles "andtheeyes of the operator.

In such machines' there isusually provided a highly rotating operatingwheel'such asfan abrasive wheel or circular saw and below the point `ofthe Wheel to which the operator-applies the `articles he is working on,there is provided a restorA base plate.

Such machinesare usually of the bench type,

'""thatis, theyare relatively small and areespecially adapted to besecured upon a Work bench, andlas'considerable oithe'work done upon suchmachines is of a 'very ne type especially in the 'manufacture of jewelrythe operator is placed with his eyes rather yclose downv toward theworking point thus exposing them tothe ying particles and especiallysuch particles which may be driven down upon the Vrest plate and whichrebound upwards' towards the eyes of the operator.

As the transparent guard proper is made of i glass, it acts as a reectorand it sometimes happens thata light is 'reilected into theeyes of the.operator fromfthe guard, this prevents the 'operator seeing clearly justwhat he is doing, land'it'is oneim'portant point of the inventionthatthe guard is so mounted that it can be readily tipped slightly atleast enoughto avoid such reflection but not interfere with a clear Viewof thepoint of operation.

In operation upon metal articles made of the precious metalsjwithout theguard, the particles rebound from the rest plate and are widelyscattered, but with the use of the guard the particles are directed backupon the base plate where they accumulate and can be readily saved.

The invention will be more readily understood by reference to theaccompanying drawing forming part of this specification and in which Ihave portrayed a grinding or abrasive wheel provided with a guard madein accordance with the invention. It shouldbe understood that suchshowing istypical merely of the application of theiguard to the manydifferent machines and situations where it will `be of benefit.

-The invention is more specifically set forth 'I i in the'appendedclaims and it is to be clearly understood that the scope of the claimsisnot vto be in any wise limited to the specific details of constructionand application herein shown and "described except where such specificlimitations "aref incorporated in the claims.

In said drawing:

'Figgl isa side elevation of `aV grinding machine lequippedvvith'a guardin accordance with my invention;

fFigJ 2 is .a fragmentary, top' plan :view ci the assembly 'shown' inFig. 1;

Fig.- 3'is a-fragmentarmtop plan View of the guard proper; l and Fig. 4is a fragmentary,` sectional view on the-1 lines 4-'4 of Figs. 1 and 3.

The grinding' machine shown in' the drawing, `as has` been explained istypical of any suitable 'machine to which the guard may be applied andcomprisesa base orframe Illladapted to be4 -securediipon a` work benchor` tableII` and car- 'ries ahorizontal rotatableshaft4 I2 iin suitablebearings I3 and'thisshaft carries a 'grinding wheel I4 rotatably securedon the shaft. The shaft I2 may be rotated by vany suitable means,- `notshown,` and the grinding wheel I4 is rotated '-with the shaft, in thedirection of the arrow on Fig. 1. AAsheet metal guard I5 is usually'pro-Yvidedwhich is -upstanding from the base at the Vrear'of the -wheelIdvand is curved over the upper 'part thereof asbest shown infFig. 1. Atthe front or vworking'side of thev Wheel there is usually provided arest or base plate I6 arranged horizontally as shown and below theApoint I'I on the 'periphery of thewheel where `the work I8 isl appliedto the wheel.

'Theguard of the invention designated generally by I9 comprises a `glassplate which may be plate glass but is preferably what is known rasunbreakable safety glass, and also though not` Anecessarily a secondsheet of glass 2l is arranged below and in iiat contact with the plate20 and these two plates are clamped tightly together by a clamping andguard mounting bolt structure designated generally by 22.

The top plate 20 is provided with a hole 23 about midway between itsends and adjacent to one edge to receive the bolt structure 22, and thelower plate 2| is provided with a similar hole 24 registering with thehole 23 and for the same purpose.

The guard I9 is mounted in position by means of the bolt structure 22upon the forward end of the sheet metal guard I which is provided with ahole 25 for this purpose.

As shown in dotted lines 26--21 in Fig. 1, the particles thrown oil' bythe wheel I4 strike the rest plate I6 and rebound upwardly. When theguard I9 is in place the particles hit the underside of the lower plate2I and are directed back to the rest plate but by this time their speedis so reduced that most of them accumulate on the rest plate IB. In suchstoppage of the upward moving particles the guard I9 performs itsfunction of protecting the eyes of the operator which are usuallypositioned above the guard plate and in the line of travel of saidparticles.

The continual impingement of the particles on the underside of the guardI9 tends to cut the said lower surface and nally to cloud it to such anextent that the glass has to be renewed. Instead of exposing the lowerface of the main sheet 29 to the grinding action of the impingingparticles, and which main sheet is more or less expensive, I protect itslower surface by the lower guard plate 2l, which can be made of muchless expensive glass and can be renewed when needed at small cost.

The bolt structure 22 by which the two sheets of the guard I9 areclamped together and by which the guard I9 is mounted on the sheet metalguard I5 includes a universal or ball joint so that the guard I9 can bereadily tipped slightly one way or the other as may be necessary.

In the use of such grinders it frequently happens that an illuminatinglamp will be so positioned that the operator will see the reflection ofthe light in the guard I9 when operating the grinder. It is obvious thatwhen this condition arises a slight tipping of the guard I9longitudinally will carry the light reflection o of the guard andeliminate this hindrance to good work.

'I'he bolt or mounting assembly 22 comprises a tubular member 28 whichis exteriorly screw threaded to receive a clamping nut 29 on its upperend and a clamping nut 30 on its lower end. The tube 28 ts loosely inthe holes 23 and 24 in the glass plates and I preferably arrangeslightly yielding washers 3| between the glass plates and said nuts toavoid possible breakage of the plates. The lower nut 30 is extended downin tubular form and is exteriorly screw threaded on its lower end 32 toreceive a nut member 33. The nut member 33 is provided at its lower sidewith an internal flange 34 which is formed at its inner edge to fit upona ball-like member 35. Between the ball 35 and the lower end of the tube28 I arrange a compression spring 3E and between the lower end of thespring 35 and the ball 35 I arrange a ring 3l which is formed on itslower side to t upon the upper surface of said ball 35. By screwing thenut member 33 up the ball 35 is clamped in place by a yielding pressure,due to the spring 36. The ball 35 is formed on the upper end of astem-like member 38 and which extends downwardly from the ball and itslower end is exteriorly screw threaded to receive a clamping nut 39 andthe member 38 is provided with an external circumferential collar 40above its lower end.

In mounting the guard I9 on the sheet metal guard I5, the lower end ofthe stem 38 is entered through the hole 25 in the guard I5 and istightly clamped thereon by the nut 39. The universal or ball connectionas described, allows the guard I9 to be tipped to suit the conditionsand the friction on the ball 35 holds the guard I9 rmly in its adjustedposition. At times it may be necessary to remove the guard I9 out of itsoperating position to permit certain forms of Work to be presented tothe wheel I4. This is accomplished by swinging the guard I9 aroundthrough 180 degrees as shown in dotted lines in Figs. 1 and 2.

As the collar 40 is quite limited as to diameter due to the necessity ofits passing through the opening in the clamping nut 33, I preferablyprovide a metal washer 4I between the collar 39 and the guard I5 toincrease the area of contact and to hold the guard I9 more firmly inposition.

To protect the glass plates 20 and 2I from possible chipping or fractureby reason of contact in the holes 23 and 24 with the metallic connectingtube 28, I arrange a non-metallic tube 42 on the metal connecting tube28. Preferably the tube 42, which is in the nature of a bushing, is madeof some material such as rubber which is at least slightly yielding soas to avoid all strain on the glass at this point.

As many modifications of the invention will readily suggest themselvesto one skilled in the art, I do not limit or conne the invention to thespecic details of construction and operation herein shown and describedexcept within the scope of the appended claims.

I claim:-

l. A device of the character described comprising a glass guard platehaving a hole therethrough and a resilient bushing in said hole, andmeans for mounting said guard plate, said means comprising a boltextending through said bushing, means on said bolt for clamping saidguard plate thereon and permitting rotative adjustment of said guardplate about said bolt, said clamping means including resilient washerson said bolt in contact with said guard plate, and means for attachingsaid bolt to a fixed support.

2. A device of the character described comprising a .glass guard platehaving a hole therethrough, a protective sheet of cheaper transparentmaterial arranged below said plate and having a hole therethrough, andmeans for mounting said plate and said sheet in superposed relation,said means comprising a bolt extending through said holes, means forattaching said bolt to a iixed support, and means adjacent the free endof said bolt for clamping said plate and said sheet removably togetherupon said bolt and permitting their rotative adjustment about said bolt.

EDWARD BRUNS.

